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  • We learn about conservation of energy in school.

  • How you can take potential energy,

  • like the energy in the chemicals in this battery,

  • and you can then just convert it to electrical energy.

  • And then convert that to whatever you can find a use for.

  • A battery is just a store of potential energy.

  • And that potential energy could be chemical,

  • or it could be gravitational.

  • This lake in this rainy bit of Wales is part of the largest battery in Britain.

  • And it's rechargeable.

  • Welcome to Dinorwig Power Station,

  • otherwise known as Electric Mountain.

  • - What we have is a large reservoir at the top of the mountain,

  • a large reservoir at the bottom,

  • and between the two, a power station,

  • which converts that potential energy into electricity.

  • The power station itself is located inside that mountain in deep caverns.

  • We release that potential energy through the station.

  • It drives a turbine that spins round at synchronous speeds, connected to the grid.

  • It drives a generator, converting that into electricity.

  • We then export that onto the National Grid.

  • And then at nighttime, we just reverse the whole process.

  • The turbine turns into a pump. The generator becomes a motor.

  • And we push that water back up the hill into the reservoir at Marchlyn Mawr,

  • at the top of the mountain.

  • The operating principle here is that the generation

  • that the station is able to do during the daytime

  • helps the nation meet those peaks of electricity demand.

  • And overnight, it's able to pump the water back when prices are lower.

  • In electrical terms, we have around nine gigawatt-hours

  • of storage at the top of the mountain.

  • And in fact over the course of a day,

  • the water passing through the station is broadly equivalent

  • to the total household consumption of water in the UK.

  • At full load, we can be meeting the demand

  • of around about two million homes.

  • - This sounds like a really simple idea,

  • but when there's this much energy involved,

  • the design challenges are ridiculous.

  • If you've ever lived in a house where you turn off a water tap

  • and the the pipes go clunk,

  • then you know about water hammer.

  • Water isn't compressible, so closing a tap

  • means that all the water that is under pressure

  • and rushing down the pipe suddenly has nowhere to go.

  • So if the pipes in your house aren't secured properly,

  • the crash and rebound of all that water

  • can make the plumbing move and make noise.

  • If that can happen with just a tap in a house,

  • imagine what could happen when one of the valves here closes.

  • At full capacity, there is somewhere around

  • a swimming pool every second

  • rushing through the turbines down there.

  • When that valve closes, all that water heading down here

  • suddenly has nowhere to go.

  • The pressure would do enormous amounts of damage.

  • It would break everything apart, if it wasn't for one extra bit of plumbing.

  • A shaft hundreds of metres deep that acts as a pressure release.

  • We can't see anything, on the surface or from down here, sadly,

  • it all happens deep within the mountain.

  • But every time those valves move,

  • [valve clanking]

  • that surge pipe is what stops the whole system

  • from tearing itself apart.

  • This station is not some quirky old curiosity.

  • This is serious engineering

  • that keeps the lights on around the country.

  • - Dinorwig Power Station is one of the largest

  • power stations of its type in the world,

  • and it's also one of the fastest-acting power stations.

  • So as well as being able to take advantage

  • of the peaks and troughs in the electricity market,

  • it was essentially built, primarily,

  • with the intent to provide very fast response onto the system

  • in order to help the National Grid balance supply and demand instantaneously

  • on a second-by-second basis.

  • So it has the capacity to be able to go from zero up to its full capacity,

  • maybe 2,000 megawatts, within 10 to 30 seconds.

  • When people talk about pumped storage,

  • they tend to associate it a lot with TV pickups,

  • and National Grid, in analysing that risk,

  • study the TV schedules and plan ahead and put Dinorwig on standby, if you like,

  • to be able to meet those pickups.

  • Going back to the 80s and the 90s,

  • everyone would be sitting around the same TV channels

  • with a limited choice, then.

  • All the ingredients you need for a sort-of collective putting-on of the kettle

  • and opening of the fridge. Pickups could be pretty significant.

  • But since then, people are streaming on YouTube, on Netflix,

  • all the different plethora of channels that we have, so that has changed

  • that sort of coincidence of viewing on one channel.

  • The current environment that we're in,

  • we have significant amount of renewable technology on the system, which provides

  • a level of unpredictability day to day.

  • And actually, the importance of storage now

  • is that we can use it to help develop the amount of renewables we have

  • and allow us to fill in those gaps

  • when the wind's not blowing and the sun is not shining.

  • So having storage is such an important component of the modern grid system.

  • - Thank you very much to all the team at Engie

  • who made this visit possible.

  • Pull down the description for more about them,

  • and more about Electric Mountain.

  • A battery is just... a store!... of potential energy.

We learn about conservation of energy in school.

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Britain's Largest Battery Is Actually A Lake

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    林宜悉 posted on 2020/04/01
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